[PATCH] Allow NULL pointers in percpu_free

The patch (as824b) makes percpu_free() ignore NULL arguments, as one would
expect for a deallocation routine.  (Note that free_percpu is #defined as
percpu_free in include/linux/percpu.h.) A few callers are updated to remove
now-unneeded tests for NULL.  A few other callers already seem to assume
that passing a NULL pointer to percpu_free() is okay!

The patch also removes an unnecessary NULL check in percpu_depopulate().

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 10 insertions, 14 deletions

diff --git a/arch/i386/kernel/acpi/cstate.c b/arch/i386/kernel/acpi/cstate.c
index 4664b55f623..12e937c1ce4 100644
--- a/arch/i386/kernel/acpi/cstate.c
+++ b/arch/i386/kernel/acpi/cstate.c
@@ -156,10 +156,8 @@ static int __init ffh_cstate_init(void)
 
 static void __exit ffh_cstate_exit(void)
 {
-        if (cpu_cstate_entry) {
-                free_percpu(cpu_cstate_entry);
-                cpu_cstate_entry = NULL;
-        }
+        free_percpu(cpu_cstate_entry);
+        cpu_cstate_entry = NULL;
 }
 
 arch_initcall(ffh_cstate_init);
diff --git a/block/blktrace.c b/block/blktrace.c
index 74e02c04b2d..d3679dd1d22 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -394,8 +394,7 @@ err:
         if (bt) {
                 if (bt->dropped_file)
                         debugfs_remove(bt->dropped_file);
-                if (bt->sequence)
-                        free_percpu(bt->sequence);
+                free_percpu(bt->sequence);
                 if (bt->rchan)
                         relay_close(bt->rchan);
                 kfree(bt);
diff --git a/mm/allocpercpu.c b/mm/allocpercpu.c
index eaa9abeea53..b2486cf887a 100644
--- a/mm/allocpercpu.c
+++ b/mm/allocpercpu.c
@@ -17,10 +17,9 @@
 void percpu_depopulate(void *__pdata, int cpu)
 {
         struct percpu_data *pdata = __percpu_disguise(__pdata);
-        if (pdata->ptrs[cpu]) {
-                kfree(pdata->ptrs[cpu]);
-                pdata->ptrs[cpu] = NULL;
-        }
+
+        kfree(pdata->ptrs[cpu]);
+        pdata->ptrs[cpu] = NULL;
 }
 EXPORT_SYMBOL_GPL(percpu_depopulate);
 
@@ -123,6 +122,8 @@ EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
  */
 void percpu_free(void *__pdata)
 {
+        if (unlikely(!__pdata))
+                return;
         __percpu_depopulate_mask(__pdata, &cpu_possible_map);
         kfree(__percpu_disguise(__pdata));
 }
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 87c8f54872b..e5cd83b2205 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -720,10 +720,8 @@ snmp6_mib_free(void *ptr[2])
 {
         if (ptr == NULL)
                 return;
-        if (ptr[0])
-                free_percpu(ptr[0]);
-        if (ptr[1])
-                free_percpu(ptr[1]);
+        free_percpu(ptr[0]);
+        free_percpu(ptr[1]);
         ptr[0] = ptr[1] = NULL;
 }